1. Field of the Invention
The present invention relates to electrical and electronic circuits and components. More specifically, the present invention relates to micro-electromechanical (MEM) switches.
2. Description of the Related Art
An electrostatic MEM switch is a switch operated by an electrostatic charge and manufactured using micro-electromechanical techniques. A MEM switch may control electrical, mechanical, or optical signal flow. Current MEM switches are usually single pole, single throw (SPST) configurations having a rest state that is normally open. Application of an electrostatic charge to the control electrode (or opposite polarity electrostatic charges to a two-electrode design) will create an attractive electrostatic force ("pull") on the switch causing the switch to close. Currently, the switch opens by removal of the electrostatic charge on the control electrode(s), allowing the mechanical spring restoration force of the armature to open the switch.
Unfortunately, electrostatically actuated MEM switches constructed in accordance with conventional teachings typically close faster than they open and often suffer "stiction" effects that hinder the opening process or cause the switch to fail closed. Hence, the opening and closing ("transition speed") of conventional MEM switches has some limitations.
For many current applications, there was a need to increase the transition speed of a MEM switch. U.S. patent application Ser. No. 09/198,669, filed Nov. 23, 1998, by the present Applicants (R. D. Streeter et al.) and entitled METHOD AND APPARATUS FOR AN IMPROVED MICRO-ELECTRICAL MECHANICAL SWITCH, the teachings of which are incorporated herein by reference, addresses the need in the art for a MEM switch having an improved transition speed. However, the switch disclosed by Streeter et al. is a single pole, single throw switch.
For certain current applications, there is a need for a single pole, double throw MEM switch having a high transition speed. Hence, a need remains in the art for further improvements in MEM switches.